1. Field of the Invention
The present invention relates to an image forming apparatus that restricts functions that can be utilized for specific documents, such as confidential documents, and to a method for controlling the image forming apparatus.
2. Description of Related Art
In recent years, image forming apparatuses (such as printers, FAX, copiers, and multifunction machines) improve the image quality of image forming apparatuses and increase a number of functions included in the apparatuses. The image forming apparatuses restrict functions (such as an image forming process) that can be utilized for specific documents which contain specific document images, such as confidential documents or color documents, based on the user.
For example, when a specific document image is included in document image data read by a scanner unit of a color copier, the color copier prohibits a printer unit from reproducing the document image. A control center receives communication from a user of the color copier in a reproduction prohibited state, notifies the user of a password for the color copier. After that, the user enters a predetermined password into the color copier. The color copier then releases the prohibited reproduction and reproduces the document image (refer to Related Art 1 for an example).
Another copier has a reader/writer which can read RFID (Radio Frequency Identification) cards that can be carried by users as well as RFID sheets attached to confidential documents. The copier reads the RFID sheets of the documents set in the copier and RFID cards of users standing in the front of the copier. The copier is controlled to allow reproductions of these documents only when the access rights of the users read from the user's RFID card is higher than the level of confidentiality of the documents read from the RFID sheet of the documents set in the copier (refer to Related Art 2 for an example).                [Related Art 1] Japanese Patent Laid-open Publication 2003-050525 (FIG. 1)        [Related Art 2] Japanese Patent Laid-open Publication 2001-160117 (FIG. 2)        
However, the following problems occurred in the conventional technologies.
The conventional copier required complicated operations of the user. In other words, when specific document images were included in the read document image data, the copier prohibited the printer unit from reproducing the document image data. The copier waited for the input of the password by the user to reproduce the document image data. Thus, the user had to contact the control center, and then the user had to enter, into the copier, the password received from the control center. These operations were very complicated for the user.
The another conventional copier also required complicated operations of the user. Further, the another copier increased cost. Only when the access rights of a user read from the user's RFID card was higher than the level of confidentiality of the documents read from the RFID of the documents set in the copier, the copier allowed reproductions of these documents. Thus, RFID sheets had to be attached to specific documents. This increased cost. Furthermore, this problem also reduced the quality of the specific documents.